The Research Of WDM-PON Based On Combined Modulation And Signals Broadcasting

Compared to EPON and GPON, WDM-PON has a simple framework and does not consist of the following series of sophisticated techniques such as burst-mode transmitter and receiver, as well as dynamic bandwidth allocation, ranging and precise control of latency. While WDM-PON can provide significant bandwidth, bit transparency, smooth upgradation, reliable QoS, as well as excellent security and confidentiality etc., it has attracted more and more attention of scholars and communication operators. With the reduction of price of optoelectronic devices, WDM-PON will necessarily play an important role in the next generation of optical access network.This thesis mainly discussed the issues regarding implementation of the WDM-PON system and formation of its network structure after the introduction of the WDM-PON key techniques. The thesis can be outlined as follows:1,Firstly, we propose a novel OFSK transmitter based on phase/polarization combined modulation format, and apply the above OFSK transmitter into WDM-PON with 2.5Gb/s downstream OFSK signals and 2.5Gb/s upstream ASK signals to make it much simpler and operate at the data rate only limited by the external modulator. It shows that demodulated OFSK signals embody smaller power penalty for both the downstream case and upstream case without any dispersion compensation. Moreover, the above modulation format can keep the intensity of optical carrier constant, and it can be combined with orthogonal modulations, and also be little affected by the nonlinear effects of fiber.2,Secondly, to solve the light source technical problems in the presence of WDM-PON, we propose a low-lost light source solution based on wavelength injection-locked FP-LD and set up one experimental system; Participate in the development of an optical transmitter based on wavelength injection-locked technology and propose temperature and light control solutions for the optical transmitter.3,Lastly, a cost-effective approach for analog or digital Cable Television (CATV) signal transmission over a Wavelength Division Multiplexing Passive Optical Network (WDM-PON) is proposed and downstream transmission performance for CATV signal is simulated. The numerical analysis shows that SNR can reach above 43dB at the bandwidth of 750MHZ, thus meets the need of CATV transmission over fiber to the home. From the experiment result, it is seen that EDFA can effectively suppress the relatively intensity noise, improving SNR by 3～4dB. Then an experimental scheme is designed to simultaneously transmit unicast and broadcast signals. It justs need some simple modulator and demodulator devices when we apply the ASK-DPSK combined modulation format to the downstream transmission of WDM-PON. It can not only double the spectral efficiency, and also achieve the selectivity of signal broadcasting.